Question about current system

[Dawelio]

Hey guys,

So to keep this short, I'll just crack on with it...

i7 2600K 3.4GHz
ASUS P8Z77-I Deluxe
16GB Corsair Vengeance Pro 1600MHz
Sapphire Radeon HD6950 2GB
Samsung 840 EVO or Pro 256GB
Corsair Force Series 3 180GB
Western Digital Caviar Green 3TB
Western digital Raptor 160GB
Silverstone 650W short psu with short cable kit
Corsair Graphite 380T

Question: Could I upgrade to an Sapphire R9 290 Vapor-X?... or would I need to change the PSU out for an 750W or 850W?...

Thanks!

Regards,
Chrazey